US20130144295A1

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Publication number: US20130144295A1
Application number: US13/672,454
Authority: US
Inventors: John To
Original assignee: OuroBoros Medical Inc
Current assignee: DePuy Synthes Products Inc
Priority date: 2011-12-03
Filing date: 2012-11-08
Publication date: 2013-06-06
Anticipated expiration: 2032-08-22
Also published as: JP6116066B2; EP2785264A4; CN103327913A; CN103327913B; JP2015083137A; JP2014513571A; US9119659B2; EP2785264A1; ES2564513T3; US20130144292A1; EP2785264B1; KR20140109924A; US10448967B2; JP5723035B2; WO2013081691A1; US9220528B2; US20130144320A1; US8663227B2; HK1197964A2; US20140358170A1

Abstract

Single-unit cutting head systems for safe removal of nucleus pulposis tissue are provided. The cutting heads compose a part of the systems that are provided to address several problems, including clogging of state-of-the-art systems during removal of such tissue, for example. The target tissue can include any tissue that is accessible through a small surgical opening, for example, a joint tissue such as a meniscus or an intervertebral tissue, such as a nucleus pulposus. The devices can be referred to as orthopedic tissue removal devices having cutting heads associated with vacuum systems, making the systems useful in several procedures, including X-LIF (lateral approach to an intervertebral fusions) procedures, T-LIF (transforaminal approach to intervertebral fusions) procedures, P-LIF (posterior approach to intervertebral fusions), and a percutaneous, transforaminal approach (Kambin triangle access).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 13/592,307, filed Aug. 22, 2012, which claims the benefit of U.S. Provisional Application No. 61/566,629, filed Dec. 3, 2011, and U.S. Provisional Application No. 61/596,865, filed Feb. 9, 2012, each application of which is hereby incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The teachings provided herein are generally directed to a safe and efficient cutting head for removing a target tissue from a subject during a surgical procedure.

2. Description of the Related Art

Intervertebral disc disease is a major worldwide health problem. In the United States alone almost 700,000 spine procedures are performed each year and the total cost of treatment of back pain exceeds $30 billion. Age related changes in the disc include diminished water content in the nucleus and increased collagen content by the 4.sup.th decade of life. Loss of water binding by the nucleus results in more compressive loading of the annulus. This renders the annulus more susceptible to delamination and damage. Damage to the annulus, in turn, accelerates disc degeneration and degeneration of surrounding tissues such as the facet joints.

The two most common spinal surgical procedures performed are discectomy and spinal fusion. These procedures only address the symptom of lower back pain, nerve compression, instability and deformity. The objective of the spinal disc fusion procedure is to restore, maintain and stabilize disc height, and/or reduce back pain. The procedure is generally performed by removing central disc material such and inner annulus, nucleus pulposus and the cartilage on the endplates before replacing with bone graft and a scaffold to effect fusion of the vertebral bodies within the treated disc for height stabilization. This removal process is called a discectomy and is both tedious and frequently inadequate which can result in compromised fusion, as well as traumatic and time consuming due to the large incision and dissections required to expose the disc for discectomy.

In a typical discectomy procedure, a nucleotomy is first performed in which the nucleus is loosened by using a curette or a manual shaver to shear the nucleus loose and then removed using a rigid grasper called a rongeur. The surgeon has to insert the rongeur through an opening in the disc called an anulotomy, grasp nucleus and remove out of the disc and the surgical access, clean the jaws and reinsert for more grasping of disc repeatedly. This process can pose safety issues for tissues in between tool passage such as nerves. Furthermore, disc debris left behind can hinder efficient subsequent tissue removal and insertion of the discectomy tools into the disc. The second step is decortication in which cartilage attached to the bone (cartilaginous endplate) is removed by the use of rigid scrapers such as a curette or a rasp to help promote a strong intervertebral fusion. Peeled cartilage are removed by scooping with a curette and withdrawn out of the body by the use of a rongeur. Tissue debris left behind can also compromise efficiency and effectiveness of the decortication resulting in a weaker fusion. Moreover, corners inside the discs are often hard to reach by current state-of-the art tools, often leaving additional areas of inadequate disc removal.

In addition, state-of-the-art systems using a combination of suction and cutting suffer clogging problems due to excised tissue becoming lodged in the system. One of skill will appreciate that problems with clogging during a surgical procedure can be problematic, and a solution to such clogging problems is highly desired.

Although several advanced tools have been developed, none have addressed all of these issues adequately. One of skill in the art would certainly appreciate a discectomy system that is (i) less tedious and time consuming to use, (ii) less prone to clogging by excised tissue; (iii) safer to the subject undergoing the surgery, and (iv) more effective in promoting a strong intervertebral fusion.

SUMMARY

The teachings provided herein are generally directed to a safe and efficient cutting head for removing a target tissue from a subject during a surgical procedure. The target tissue can include any tissue that is accessible through a small surgical opening, for example, a joint tissue such as a meniscus, in some embodiments, or an intervertebral tissue, such as a nucleus pulposus, in other embodiments.

The cutting head can be tubular with a cutting surface forming at least a first plane on a distal perimeter of cutting head, the cutting head in operable communication with a suction device to excise a target tissue in a manner that facilitates an ease of removal of the tissue with the suction. The cutting surface can be flat, sinusoidal, or serrated, for example, and the first plane of the cutting surface may be at an angle, θ_FP, that deviates up to 75° from a position that is orthogonal to the central axis of the cutting head. In some embodiments, the cutting surface can have a second plane may be at an angle, θ_SP, that deviates up to 75° from a position that is orthogonal to the central axis of the cutting head. In some embodiments, the cutting head has a cutting blade and a blade guard for guarding a perimeter tissue from the cutting blade.

As such, the teachings include a tubular cutting head for removing a target tissue of a subject. In these embodiments, the cutting head can have an outer perimeter that circumscribes a lumen through the cutting head, the lumen having a central axis. The cutting head can also have a forward cutting blade on a distal edge of the outer perimeter, the forward cutting blade configured for (i) cutting a target tissue in a forward stroke of the cutting head and (ii) directing the cut tissue into the lumen. And, the cutting head can also have a blade guard positioned distal to the forward cutting blade and configured to guard a perimeter tissue from the forward cutting blade upon the forward stroke the blade guard having a width that is smaller than the width of a transverse cross-section of the lumen to facilitate entry of the target tissue into the lumen on the forward stroke.

In some embodiments, the cutting head can have a backward cutting blade for cutting the target tissue in a backward stroke of the cutting head, a transverse cutting blade for cutting the target tissue in a transverse stroke of the cutting head, or a combination thereof. In some embodiments, a transverse cutting blade can be positioned on the blade guard for cutting the target tissue in a transverse stroke of the cutting head.

In some embodiments, the backward cutting blade can be positioned on the distal edge of the outer perimeter for cutting the target tissue in the backward stroke of the cutting head. In some embodiments, the backward cutting blade can be positioned on the blade guard for cutting the target tissue in the backward stroke of the cutting head, the blade guard having a double-edged blade tip point back into the lumen at an angle, θ₂, of greater than 90° to trap and/or cut tissue in the lumen in the backwards stroke of the cutting head.

Since the cutting head can be designed to remove tissue through use of a suction, the teachings are also directed to systems of a cutting head that operably connect the cutting head with a suction assembly. As such, the teachings include a such a surgical, tissue removal system that includes a tubular cutting head for removing a target tissue of a subject. The system can include a cutting head having an outer perimeter that circumscribes a flow of suction through the cutting head; a lumen circumscribed by the outer perimeter, the lumen guiding the flow of suction and having a central axis; a forward cutting blade on a distal edge of the outer perimeter, the forward cutting blade configured for (i) cutting the target tissue in a forward stroke of the cutting head and (ii) directing the cut tissue into the lumen; and, a blade guard positioned distal to the forward cutting blade and configured to guard a perimeter tissue from the forward cutting blade upon the forward stroke the blade guard. In some embodiments, the blade guard can have a width that is smaller than the width of a transverse cross-section of lumen to facilitate entry of the target tissue into the lumen on the forward stroke.

The cutting head can be configured for an operable communication between the lumen and a source of a suction, such that the systems include a suction assembly in operable communication with the cutting head for creating the flow of suction for removing the target tissue through the lumen and out of the subject, the suction assembly comprising a rigid suction tube with a central axis. In some embodiments, the operable communication includes the use of one or more suction ports positioned just proximal to the most proximal point of the distal edge of the out perimeter of the cutting head. In some embodiments, the one or more ports can be located from about 3 mm to about 20 mm proximal to the most proximal point of the distal edge.

In some embodiments, the suction assembly comprises an at least substantially rigid suction tube having a proximal end and a distal end, the distal end in the operable communication with the cutting head, and the distal end configured for communicating with a source of suction for the suction assembly. In some embodiments, the at least substantially rigid suction tube can be formed as a single unit with the cutting head.

In some embodiments, the central axis of the lumen is at an angle, θ₁, ranging from about 5° to about 90° from the central axis of the rigid suction tube, and the forward cutting blade is located about 3 mm to about 25 mm from the vertex of the angle, θ₁.

The system of claim10, the central axis of the lumen has a point of exit at the forward cutting blade, and the point of exit is located at a transverse distance of about 3 mm to about 25 mm that is orthogonal to the central axis of the rigid suction tube.

In some embodiments, the central axis of the lumen can be at an angle, θ₁, ranging from about 5° to about 90° from a central axis of the flow of suction at the distal end of the suction assembly, and the forward cutting blade can be located about 3 mm to about 25 mm from the vertex of the angle, θ₁. In some embodiments, the operable communication between the cutting head and the suction assembly can be articulating, and the angle can be adjustable. In some embodiments, the operable communication between the cutting head and the suction assembly can be rigid, and the angle can be fixed.

In some embodiments, the central axis of the lumen is at an angle, θ₁, ranging from 1° to 180° from a central axis of the flow of suction at the distal end of the suction assembly, and the forward cutting blade is located 3 mm to 25 mm from the vertex of the angle, θ₁. In these embodiments, additional angle, θ₃, is located 5 mm to 25 mm proximal to θ₁, and angles θ₁and θ₃are independently selected to range from about 0° to about 180°, with the limitation that (i) the net angle, θ₄, between the central axis of the lumen of the cutting head and the central axis of a rigid suction tube located proximal to θ₃ranges from 0° to 90°; and, (ii) the distance between the central axis of the lumen of the cutting head and the central axis of the rigid suction tube ranges from 2 mm to 30 mm.

It should be appreciated that the cutting heads and systems taught herein have a variety of applications known to one of skill. In some embodiments, the target tissue can be a nucleus pulposus, and the perimeter tissue can be an annulus fibrosis, for example.

As such, the teachings are also directed to a surgical, tissue removal system for a discectomy, and the systems can comprise a tubular cutting head for removing a nucleus pulposus from a subject. In these embodiments, the systems can include a cutting head having an outer perimeter that circumscribes a flow of suction through the cutting head; a lumen circumscribed by the outer perimeter, the lumen guiding the flow of suction; a forward cutting blade on a distal edge of the outer perimeter, the forward cutting blade configured for (i) cutting the nucleus pulposus in a forward stroke of the cutting head and (ii) directing the cut nucleus pulposus into the lumen; a backward cutting blade for cutting the nucleus pulposus in a backward stroke of the cutting head; a transverse cutting blade for cutting the nucleus pulposus in a transverse stroke of the cutting head; and, a blade guard positioned distal to the forward cutting blade and configured to guard an annulus fibrosis tissue from the forward cutting blade upon the forward stroke. And, the blade guard can have a width, for example, that is smaller than the width of a transverse cross-section of the lumen to facilitate entry of the target tissue into the lumen on the forward stroke.

The teachings also include a method of removing a target tissue from a subject. In these embodiments, the method can comprise creating an opening in a subject for access to a target tissue; inserting a cutting head taught herein through the opening to access the target tissue in the subject; and, forcing the cutting head in a forward direction on a surface comprising the target tissue to remove the target tissue. The forward direction can include a force vector that moves (i) at least substantially on a plane containing the central axis of the lumen of the cutting head, (ii) at least substantially on the surface comprising the target tissue, and (iii) toward the perimeter tissue that is protected by the blade guard. And, the method can include capturing the target tissue in the lumen of the cutting head, as well as removing the target tissue through the lumen and out of the subject.

In some embodiments, the method comprises forcing a cutting head taught herein in a backward direction on a surface comprising the target tissue to remove the target tissue. The backward direction can include a force vector that moves (i) at least substantially on a plane containing the central axis of the lumen of the cutting head, (ii) at least substantially on the surface comprising the target tissue, and (iii) away from the perimeter tissue that is protected by the blade guard.

In some embodiments, the method comprises forcing a cutting head taught herein in a transverse direction on a surface comprising the target tissue to remove the target tissue. The transverse direction can include a force vector that moves (i) at an angle ranging from about 15° to about 150° from a plane containing the central axis of the lumen of the cutting head, (ii) at least substantially on the surface comprising the target tissue, and (iii) in contact with the perimeter tissue that is protected by the blade guard.

The teachings are also directed to an obturator, guard cannula to protect a subject during entry and exit of an elongated surgical cutting device having a non-linearity. In these embodiments, the guard cannula can comprise an entry hub having an inner perimeter, an outer perimeter, and an irrigation port that communicates between the inner perimeter with the outer perimeter; and, a linear, elongated split-tube having a proximal end, a distal end, and a lumen. In these embodiments, the proximal end of the split-tube can (i) circumscribe at least a portion of the inner perimeter of the hub and (ii) be in operable communication with the irrigation port. In these embodiments, the communication can be operable to receive an irrigation fluid from the irrigation port, the transport of the irrigation fluid to a target tissue including, for example, a movement of the irrigation fluid from the irrigation port to the distal end of the split-tube on a luminal surface of the split-tube.

The distal end of the split-tube can also have any configuration desired by one of skill. For example, the distal end can at least substantially pointed and/or sharp. In some embodiments, the distal end can be at least substantially blunt to avoid damage to an entry tissue upon contact of the distal end with the entry tissue. The split-tube can also have a length ranging from about 10 cm to about 60 cm and a width ranging from about 5 mm to about 16 mm. Moreover, the split in the split-tube can compose a gap having a width ranging from about 4 mm to about 14 mm, the split accommodating a non-linearity in the surgical device.

As described above, the systems taught herein can be used in a variety of procedures for removal of a target tissue from a subject including, for example, removal of a meniscus or a discectomy. In some embodiments, the surgical cutting device used with the guard cannula can be a discectomy device. And, in some embodiments, the entry tissue includes the subject's epithelial tissue, muscle tissue, nerve tissue, connective tissue, a blood vessel, bone, cartilage, or a combination thereof, leading to the nucleus pulposus. As such, the target tissue can include the nucleus pulposus in some embodiments.

The teachings are also directed to a surgical tissue removal kit having a surgical tissue removal system and a guard cannula, using any combination of system and cannula embodiments taught herein. In some embodiments, the kits can be a discectomy kit. As such, in some embodiments, the entry tissue includes the subject's epithelial tissue, muscle tissue, nerve tissue, connective tissue, a blood vessel, bone, cartilage, or a combination thereof, leading to the nucleus pulposus. As such, the target tissue can include the nucleus pulposus in some embodiments.

The teachings are also directed to a method of using the kits to remove a target tissue. In some embodiments, the method comprises creating an opening in a subject for access to a target tissue; inserting the cutting head of the kit through the entry hub and the elongated split-tube of the guard cannula of the kit; inserting the cutting head of the kit through the opening to access the target tissue in the subject while protecting the entry tissue with the blunt, distal end of the split-tube. Otherwise, methods of using the tissue removal systems are the same or similar to those taught herein. One of skill will appreciate having such kits for discectomies, for example, in which the target tissue can be a nucleus pulposus, and the perimeter tissue can be an annulus fibrosis. One of skill will also appreciate having a kit with a guard cannula that helps protect the subject's epithelial tissue, muscle tissue, nerve tissue, connective tissue, a blood vessel, bone, cartilage, or a combination thereof, leading to the nucleus pulposus in such procedures.

One of skill will appreciate that the embodiments taught herein are provided for purposes of outlining general concepts, and that several additional embodiments are included in, and can be derived from, the teachings provided herein.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1D illustrates a variety of tubular cutting head configurations that can be fabricated from stock tube, according to some embodiments.

FIGS. 2A-2E show blade configurations, according to some embodiments.

FIGS. 3A-3C show cross section of individual blade profiles, according to some embodiments.

FIGS. 4A-4C illustrate a cutting head, according to some embodiments.

FIGS. 5A and 5B illustrate the angulation of a cuttinghead500, according to some embodiments.

FIG. 6 illustrates an obturator, guard cannula, according to some embodiments.

FIG. 7 illustrates a surgical tissue removal kit, according to some embodiments.

FIGS. 8A-8C illustrate a system or kit that can irrigate concurrent with application of suction, and without the obturator, guard cannula in place, according to some embodiments.

FIGS. 9A-9H show cutting head designs that were tested, according to some embodiments.

FIGS. 10A-10E illustrate the advancements in the cutting head, according to some embodiments.

FIGS. 11A-11C illustrate a bayonet-type communication between a cutting head and a suction assembly, according to some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The teachings provided herein are generally directed to a safe and efficient cutting head for removing a target tissue from a subject during a surgical procedure. The target tissue can include any tissue that is accessible through a small surgical opening, for example, a joint tissue such as a meniscus or an intervertebral tissue, such as a nucleus pulposus. In some embodiments, the devices taught herein can be referred to as an orthopedic tissue removal device. In some embodiments, the devices taught herein are useful in X-LIF (lateral approach to an intervertebral fusions) procedures, T-LIF (transforaminal approach to intervertebral fusions) procedures, P-LIF (posterior approach to intervertebral fusions), or a percutaneous, transforaminal approach (Kambin triangle access).

The term “subject” and “patient” can be used interchangeably in some embodiments and refer to an animal such as a mammal including, but not limited to, non-primates such as, for example, a cow, pig, horse, cat, dog, rat and mouse; and primates such as, for example, a monkey or a human. As such, the terms “subject” and “patient” can also be applied to non-human biologic applications including, but not limited to, veterinary, companion animals, commercial livestock, and the like.

The cutting head can be tubular with a cutting surface forming at least a first plane on a distal perimeter of cutting head, the cutting head in operable communication with a suction device to excise a target tissue in a manner that facilitates an ease of removal of the tissue with the suction.

The cutting surface can be flat, sinusoidal, or serrated, for example, and the first plane of the cutting surface may be at an angle, θ_FP, that deviates up to 75° from a position that is orthogonal to the central axis of the cutting head. In some embodiments, the cutting surface can have a second plane may be at an angle, θ_SP, that deviates up to 75° from a position that is orthogonal to the central axis of the cutting head. In some embodiments, the cutting head has a cutting blade and a blade guard for guarding a perimeter tissue from the cutting blade. In some embodiments, θ_FPand θ_SPcan be independently selected to range from 0° to about 75°, from about 5° to about 75°, from about 10° to about 70°, from about 15° to about 65°, from about 10° to about 60°, from about 5° to about 55°, from about 15° to about 50°, from about 20° to about 45°, from about 15° to about 40°, from about 25° to about 35°, or any angle or range of angles therein in increments of 1°.

FIGS. 1A-1D illustrates a variety of tubular cutting head configurations that can be fabricated from stock tube, according to some embodiments.FIG. 1A shows a cuttinghead stock tube100 having afirst plane105 at an angle, θ_FP, that is orthogonal to thecentral axis110 of the lumen of thestock tube100.FIG. 1B shows a cuttinghead stock tube100 having afirst plane105 at an acute angle, θ_FP, to thecentral axis110 of the lumen of thestock tube100, the acute angle ranging from 1° to about 75°.FIG. 10 shows a cuttinghead stock tube100 having afirst plane105 at an acute angle, θ_FP, to thecentral axis110 of the lumen of thestock tube100, the acute angle, θ_FP, ranging from 1° to about 75°; and, having asecond plane105 at an angle, θ_SP, that is orthogonal to thecentral axis110 of the lumen of thestock tube100.FIG. 1D shows a cuttinghead stock tube100 having afirst plane105 at an acute angle, θ_FP, to thecentral axis110 of the lumen of thestock tube100, the acute angle ranging from 1° to about 75°; and, having asecond plane105 at an angle, θ_SP, to thecentral axis110 of the lumen of thestock tube100, the acute angle, θ_SP, ranging from 1° to about 75°.

The cutting head can be fabricated from any material known to one of skill to be suitable in a surgical environment for the uses taught herein. For example, a hard material with hardness greater than Rockwell C 30 or greater than Rockwell C 45 can be suitable in some embodiments. In some embodiments, the cutting head can be comprised of a component selected from the group consisting of tempered steel, stainless steel, high carbon steel, titanium or titanium alloy, ceramic, diamond and obsidian. In some embodiments, the stainless steel can comprise 304 stainless steel, 316 stainless steel, 17-4 PH stainless steel, 400 series stainless steel, or any other stainless steels known to one of skill to be suitable for the cutting functions taught herein. In some embodiments, the cutting head can be made of cobalt chromium, tungsten carbide, or a ceramic.

The tube forming the cutting head can have a wall thickness, for example, from 0.003″ to 0.020″ or more specifically 0.005″ to 0.012″. The cross-sectional area of the cutting head can range from 0.120 inches²to 1.5 inches²or, in some embodiments, from 0.180 in²to 0.400 in². The width in any direction can range from 0.080″ to 0.400″ or more and, in some embodiments, 0.160″ to 0.250″. In some embodiments, the cutting head can have a maximum transverse cross section dimension ranging from about 3.0 mm to about 20.0 mm, from about 4.0 mm to about 15.0 mm, from about 4.0 mm to about 12.0 mm, from about 5.0 mm to about 10.0 mm, about 5.0 mm to about 8.0 mm, or any range therein in increments of 0.1 mm. In some embodiments, the cutting heads have diameters of about 4.8 mm, about 5.0 mm, about 5.2 mm, about 5.4 mm, about 5.8 mm, about 6.0 mm, about 6.2 mm, about 6.4 mm, about 6.6 mm, about 6.8 mm, about 7.0 mm, about 7.2 mm, about 7.4 mm, about 7.6 mm, about 7.8 mm, about 8.0 mm, about 8.2 mm, and any 0.1 mm increment therein.

The distal perimeter of a cutting head can be on the first plane or the second plane, or a combination thereof, and the cutting surfaces can be any cutting surface known to one of skill, such as a razor surface, a serrated surface, or a sinusoidal surface, in some embodiments. There are a variety of possible blade configurations known to one of skill in the art of cutting blade design, and any such configuration may be used. For example, the cutting surface can have teeth and gullets between the teeth. The spacing between the teeth can be equal or variable, and the depth of the gullets can be equal or variable, and any combination of teeth and gullets can be used. In some embodiments, the direction of the protrusion of the teeth can be offset from the direction of the remainder of the walls of the cutting head. In some embodiments, the teeth are in the same direction as the remainder of the walls of the cutting head, such that the teeth are merely an extension of the walls of the cutting head, with no shift in direction toward the lumen of the cutting head or away from the lumen of the cutting head. In some embodiments, there is a pattern of directional shift of the teeth away from, or toward, the lumen of the cutting head. For example, the pattern can be a sequence of toward, away, toward, away, no shift, and the sequence is repeated around the distal edge of the outer perimeter of the cutting head. In some embodiments, all teeth can point toward the lumen, and in some embodiments, all teeth can point away from the lumen. In some embodiments, the teeth alternate toward the lumen and away from the lumen tooth-by-tooth. And, in some embodiments, the teeth are gradually toward and away from the lumen at gradually increases and decreasing angles, tooth-by-tooth, to create an appearance of waves as the teeth circle the distal edge of the outer perimeter. The sequence can also be entirely random.

FIGS. 2A-2E show blade configurations, according to some embodiments.FIG. 2A shows a 5 tooth shift pattern of toward, away, toward, away, no shift, repeat.FIG. 2B shows a random shift pattern.FIG. 2C shows a wavy shift pattern.FIG. 3D shows a 3 tooth shift pattern of away, toward, no shift, repeat. And,FIG. 3E shows a simple away, toward, repeat shift pattern.

The choice of blade configuration can be combined with a choice of blade profile, in some embodiments. Those of skill in the art of designing cutting blades will appreciate that the cutting heads taught herein can have a variety cutting actions, such as a chisel action, sawing action, slicing action, and ripping action, for example. As such, the blade profile chosen can be varied to use any blade profile known to one of skill. In some embodiments, the teeth are beveled. In some embodiments, the cutting heads have teeth that point backward as well as forward to include forward cutting surfaces in addition to backward cutting “spurs.”

As such, the teachings include a tubular cutting head for removing a target tissue of a subject. And, the tube can be an elongated, tubular structure of any shape, such as circular tube, a square tube, a rectangular tube, an elliptical tube, a pentagonal tube, a hexagonal tube, heptagonal, an octagonal tube, and the like, such that any number of sides, curvatures, or combinations thereof can be used in some embodiments. In some embodiments, a circular tube is used.

The cutting heads can have a combination of blade types, for example, forward-cutting blades, backward-cutting blades, and transverse cutting blades, as well as protrusions, hooks, and the like, for grabbing, ripping, or otherwise removing tissue. In some embodiments, the cutting head can have a backward cutting blade for cutting the target tissue in a backward stroke of the cutting head, a transverse cutting blade for cutting the target tissue in a transverse stroke of the cutting head, or a combination thereof. In some embodiments, a transverse cutting blade can be positioned on the blade guard for cutting the target tissue in a transverse stroke of the cutting head.

FIGS. 3A-3C show cross section of individual blade profiles, according to some embodiments.FIG. 3A shows a planar-concave blade profile.FIG. 3B shows a wedge blade profile. And,FIG. 3C shows a chisel blade profile. Likewise, it should be appreciated that the blades can be designed to have any configuration, including a single-edge, double-edge, single barb, double-barb, straight tip, barbed tip, and the like, to assist with any form of tissue removal, including cutting, slicing, chiseling, scraping, gouging, sawing, grinding, and ripping of a tissue for efficiency in removal during a surgery, for example.

FIGS. 4A-4C illustrate a cutting head, according to some embodiments.FIG. 4A shows an oblique view of the cutting head, andFIG. 4B shows a lateral view. The cuttinghead400 can have anouter perimeter405 that circumscribes alumen410 through the cuttinghead400, thelumen410 having acentral axis415. The cuttinghead400 can also have aforward cutting blade420 on adistal edge425 of theouter perimeter405, theforward cutting blade420 configured for (i) cutting a target tissue (not shown) in a forward stroke of the cuttinghead400 and (ii) directing the cut tissue into thelumen410. And, the cuttinghead400 can also have ablade guard430 positioned distal to theforward cutting blade420 and configured to guard a perimeter tissue (not shown) from theforward cutting blade420 upon the forward stroke theblade guard430 having awidth433 that is smaller than thewidth422 of a transverse cross-section of thelumen410 to facilitate entry of the target tissue into thelumen410 on the forward stroke. And, as shown inFIGS. 4A-4C, the lateral surfaces409 of the blade guard can also be serrated, or otherwise sharp cutting surfaces, for transverse cutting.

Since the cutting head can be designed to remove tissue through use of asuction444, the teachings are also directed to systems of a cutting head that operably connect the cutting head with a suction assembly484 (distal end only shown). As such,FIG. 4C also shows such a surgical, tissue removal system that includes atubular cutting head400 for removing a target tissue (not shown) of a subject. The system can include a cuttinghead400 having an outer perimeter that circumscribes a flow ofsuction444 through the cuttinghead400; alumen415 circumscribed by theouter perimeter405, thelumen410 guiding the flow ofsuction444 and having acentral axis415; aforward cutting blade420 on adistal edge425 of theouter perimeter405, theforward cutting blade420 configured for (i) cutting the target tissue in a forward stroke of the cuttinghead400 and (ii) directing the cut tissue into thelumen410; and, ablade guard430 positioned distal to theforward cutting blade420 and configured to guard a perimeter tissue (not shown) from theforward cutting blade420 upon the forward stroke theblade guard430.

The cutting head can be configured for an operable communication between thelumen410 and a source of thesuction444, such that thesystems400 include thesuction assembly484 in operable communication with the cuttinghead400 for creating the flow ofsuction444 for removing the target tissue through thelumen410 and out of the subject, thesuction assembly484 comprising arigid suction tube488 with a central axis. In some embodiments, the operable communication includes the use of one ormore suction ports466 positioned just proximal to the most proximal point of the distal edge of the out perimeter of the cutting head. In some embodiments, the one ormore suction ports466 can be located from about 3 mm to about 20 mm proximal to the most proximal point of thedistal edge425. While not intended to be bound by any theory or mechanism of action, one of skill will appreciate that a source of additional air can be useful when suctioning within a region that can create vacuum which would otherwise impede or cease the flow of suction that transports excised tissue away from the surgical space during the removal of the tissue. Thesuction ports466 can be used to provide the additional air to avoid creating of the vacuum in the surgical space.

Any suction assembly construction known to one of skill can be used in many embodiments. In some embodiments, thesuction assembly484 comprises an at least substantiallyrigid suction tube488 having a proximal end (not shown) and adistal end499, thedistal end499 in the operable communication with the cuttinghead400, and thedistal end499 configured for communicating with a source ofsuction444 for thesuction assembly484. In some embodiments, the at least substantiallyrigid suction tube488 can be formed as a single unit with the cuttinghead400. The phrase, “at least substantially rigid” can refer a component that is rigid, or sufficiently rigid such that the desired function is obtained, under the forces that are created with normal use. For example, a desired function may be to prevent or inhibit the occurrence of a bending moment of the rigid component at one or more points along the length of a rigid suction tube upon use of the cutting head in the subject.

The following table describes the dimensional ratios of the cuttinghead400 that were found to facilitate fast-and-efficient tissue removal in a discectomy. The “Label” is used to show the components and measures that form the ratios in a small device and a large device.


	Label

		404
402	403	Pincer	401
Cutter	Pincer	Width at the	ID-Pincer
Diameter	Height	peak of the	Tip gap
(in)	(in)	arch(in)	(in)	403/402	404/402	401/402

Small	0.203	0.098	0.080	0.085	0.483	0.394	0.419
Device
Large	0.250	0.140	0.125	0.104	0.560	0.500	0.416
Device
				Mean-->	0.521	0.447	0.417
				Theoretical	0.7	0.7	0.6
				Upper
				Limit
				Theoretical	0.3	0.3	0.3
				Lower
				Limit

The rigid suction tube can comprise any material known to one of skill to be suitable for the uses taught herein. For example, the rigid suction tube can comprise any surgical steel, plastic or resin considered desirable to one of skill for the devices taught herein. In some embodiments, the rigid suction tube can comprise the same or similar materials as the cutting head. In some embodiments, the rigid suction tube can comprise a stainless steel, polyetheretherketone (PEEK), polyimide, or carbon fiber. The wall thickness of the shaft can be any thickness at which a select material will have the physical properties desired. In some embodiments, the wall thickness can range, for example, from 0.003″ to 0.020,″ and from 0.005″ to 0.010″ in some embodiments. The luminal surface of the tube can be coated with TEFLON, a hydrophobic coating such as parylene, or a hydrophilic coating such as polyvinyl alcohol or polyethylene glycol.

In some embodiments, the rigid suction tube can comprise a polymer tube reinforced with a metal braid, a coiled tube, or a tube with transverse slots to facilitate articulation, should articulation be desired in some embodiments. In such embodiments, the cutting head can be angled relative to the axis of the rigid suction tube by, for example, pulling on a tendon attached to the cutting head on one side, the tendon running-along a guide on the side of the rigid suction tube.

FIGS. 5A and 5B illustrate the angulation of a cuttinghead500, according to some embodiments.FIG. 5A shows that thecentral axis515 of thelumen510 can be at an angle, θ₁, ranging from about 5° to about 90° from acentral axis555 of the flow ofsuction544 at the distal end599 of the suction assembly (partially shown)584, and theforward cutting blade520 can be located about 2 mm to about 25 mm from the vertex of the angle, θ₁. In some embodiments, θ₁can range from about 2 mm to about 30 mm, from about 2 mm to about 30 mm, from about 2.5 mm to about 25 mm, from about 3 mm to about 25 mm, from about 4 mm to about 20 mm, from about 5 mm to about 15 mm, from about 3 mm to about 25 mm, from about 7 mm to about 12 mm, from about 8 mm to about 10 mm, or any range therein in increments of 0.5 mm.

In some embodiments, the central axis of the lumen is at an angle, θ₁, ranging from about 5° to about 90° from the central axis of the rigid suction tube, and the forward cutting blade is located about 3 mm to about 25 mm from the vertex of the angle, θ₁. And, in some embodiments, the central axis of the lumen has a point of exit at the forward cutting blade, and the point of exit is located at a transverse distance of about 3 mm to about 25 mm that is orthogonal to the central axis of the rigid suction tube

In some embodiments, the central axis of the lumen is at an angle, θ₁, ranging from 1° to 180° from a central axis of the flow of suction at the distal end of the suction assembly, and the forward cutting blade is located 3 mm to 25 mm from the vertex of the angle, θ₁. In these embodiments, additional angle, θ₃, is located 5 mm to 25 mm proximal to θ₁, and angles θ₁and θ₃are independently selected to range from about 0° to about 180°, with the limitation that (i) the net angle, θ₄, between the central axis of the lumen of the cutting head and the central axis of a rigid suction tube located proximal to θ₃ranges from 0° to 90°; and, (ii) the distance between the central axis of the lumen of the cutting head and the central axis of the rigid suction tube ranges from 2 mm to 30 mm. As such, the distance in the flow of suction between angles θ₁and θ₃can range from about 5 mm to about 30 mm, from about 5 mm to about 25 mm, from about 5 mm to about 20 mm, from about 6 mm to about 18 mm, from about 7 mm to about 15 mm, or any range or distance therein in increments of 1 mm.

In some embodiments, the operable communication between the cuttinghead500 and thesuction assembly584 can be articulating, and the angle, θ₁, can be adjustable. In some embodiments, the operable communication between the cuttinghead500 and thesuction assembly584 can be rigid, and the angle, θ₁, can be fixed. In some embodiments, the angle, θ₁, can range from 0° to about 45°, from about 1° to about 40°, from about 5° to about 35°, from 10° to about 35°, from 15° to about 40°, from 20° to about 30°, or any range therein in increments of 1°. In some embodiments, the angle, θ₁, can be about 3°, about 5°, about 10°, about 15°, about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, or any angle therein in increments of 1°.

In some embodiments, the backward cutting blade can be positioned on thedistal edge525 of theouter perimeter505 for cutting the target tissue in the backward stroke of the cuttinghead500. In some embodiments, thebackward cutting blade531 can be positioned on theblade guard530 for cutting the target tissue in the backward stroke of the cuttinghead500.FIG. 5B shows that theblade guard530 can have a double-edged blade tip as thebackward cutting blade531 point back into thelumen515 at an angle, θ₂, of greater than 90° from thecentral axis515 of thelumen500 to trap and/or cut tissue in thelumen510 in the backwards stroke of the cuttinghead500. Thebackward cutting blade531 can be referred to as a “talon” in some embodiments, or “pincer”, as it can function to grab, shear, and hook tissue for removal.

A surgical, tissue removal system for a discectomy is provided, and the systems can comprise a tubular cutting head for removing a nucleus pulposus from a subject. In these embodiments, the systems can include a cutting head having an outer perimeter that circumscribes a flow of suction through the cutting head; a lumen circumscribed by the outer perimeter, the lumen guiding the flow of suction; a forward cutting blade on a distal edge of the outer perimeter, the forward cutting blade configured for (i) cutting the nucleus pulposus in a forward stroke of the cutting head and (ii) directing the cut nucleus pulposus into the lumen; a backward cutting blade for cutting the nucleus pulposus in a backward stroke of the cutting head; a transverse cutting blade for cutting the nucleus pulposus in a transverse stroke of the cutting head; and, a blade guard positioned distal to the forward cutting blade and configured to guard an annulus fibrosis tissue from the forward cutting blade upon the forward stroke.

The teachings also include a method of removing a target tissue from a subject. In these embodiments, the method can comprise creating an opening in a subject for access to a target tissue; inserting a cutting head taught herein through the opening to access the target tissue in the subject; imaging the depth of the tip of the cutting head using a suitable imaging technique, such as fluoroscopy; and, forcing the cutting head in a forward direction on a surface comprising the target tissue to remove the target tissue while vacuum is activated to suck cut tissue proximally. The forward direction can include a force vector that moves (i) at least substantially on a plane containing the central axis of the lumen of the cutting head, (ii) at least substantially on the surface comprising the target tissue, and (iii) toward the perimeter tissue that is protected by the blade guard. And, the method can include capturing the target tissue in the lumen of the cutting head, as well as removing the target tissue through the lumen and out of the subject.

The phrase, “at least substantially on . . . ,” can refer to a position or movement that is sufficient close to the exact desired position such that the desired function is obtained, under the forces and conditions that are created with normal use of the systems and devices taught herein. For example, “at least substantially on a plane containing the central axis of the lumen of the cutting head” or at least substantially on the surface comprising the target tissue” can refer to a position or movement that is parallel or substantially parallel to the plane or surface but perhaps off by about 1 um to about 15 mm from the actual plane, or perhaps off by about 0.1° to about 20° in direction of movement. The measure of “at least substantially” is used to approximate situations in which the exact measure or position is not obtained, but function desired by a person of ordinary skill is obtained. For example, a reduction of outcome when compared to the best possible outcome can be used to determine what is “at least substantially” the desired outcome. In some embodiments, the desired outcome is at least substantially obtained where the best possible outcome is reduced by less than 10%, less than 15%, less than 20%, less than 30%, less than 40% or less than 50%. In some embodiments, the desired outcome is at least substantially obtained where the best possible outcome is reduced by an amount of about 5% to about 30%, about 7% to about 35%, about 10% to about 25%, or any range therein in increments of 1%.

In a discectomy, the opening in the subject can vary, depending on the disk height of the subject, which is often in the range of about 5 mm-7 mm. In some embodiments, the opening in the subject can range in size from about 4 mm×4 mm to about 14 mm×14 mm. In some embodiments, the opening can be about 10 mm×7 mm.

In some embodiments, the method comprises forcing a cutting head taught herein in a transverse direction on a surface comprising the target tissue to remove the target tissue. The transverse direction, for example, can include a force vector that moves (i) at an angle ranging from about 15° to about 165° from a plane containing the central axis of the lumen of the cutting head, (ii) at least substantially on the surface comprising the target tissue, and (iii) in contact with the perimeter tissue that is protected by the blade guard.

The cutting heads taught herein are sharp and can be harmful to tissues during entry and exit of the cutting heads through the surgical opening. An obturator, guard cannula is provided in some embodiments to protect a subject during entry and exit of an elongated surgical cutting device having a non-linearity.

FIG. 6 illustrates an obturator, guard cannula, according to some embodiments. Theguard cannula600 can comprise anentry hub605 having aninner perimeter615, anouter perimeter625, and anirrigation port635 that communicates between theinner perimeter615 with theouter perimeter625; and, a linear, elongated split-tube650 having aproximal end655, adistal end665, and a lumen675. In these embodiments, theproximal end655 of the split-tube650 can (i) circumscribe at least a portion of theinner perimeter615 of thehub605 and (ii) be in operable communication with theirrigation port635. In these embodiments, the communication can be operable to receive anirrigation fluid690 from theirrigation port635, the transport of theirrigation fluid690 to a target tissue (not shown) including, for example, a movement of theirrigation fluid690 from theirrigation port635 to thedistal end665 of the split-tube650 on aluminal surface680 of the split-tube650.

One of skill will appreciate that the “irrigation fluid” can be any fluid desired by one of skill, including liquids and gases. In some embodiments, the irrigation fluid can be aqueous. In some embodiments, the irrigation fluid can be non-aqueous. And, in some embodiments, the irrigation fluid can be an emulsion. In some embodiments, the irrigation fluid can comprise a gas. Examples of aqueous irrigation fluids include water, saline, or an aqueous surfactant containing liquid. Examples of non-aqueous fluids can include any oil-based liquid that may help facilitate tissue extraction during a surgical procedure. Examples of gases can include carbon dioxide, nitrogen, air, and any inert or at least substantially non-reactive gases. In some embodiments, the irrigation fluid can include a lubricant, such as glycerin, silicon oil, and the like. Irrigation fluids can be used as a carrier to help remove an excised tissue, or to help inhibit the creation of a vacuum within a surgical site that can inhibit the removal of the excised tissue. An example of such as a vacuum is one that may be created during use of a suction within a closed cavity such as an intervertebral space within an annulus during a discectomy.

Thedistal end665 of the split-tube650 can also have any configuration desired by one of skill. For example, thedistal end665 can be at least substantially pointed and/or non-blunt. In some embodiments, thedistal end665 can be at least substantially blunt to avoid damage to an entry tissue upon contact of thedistal end665 with the entry tissue. The split-tube650 can also have a length ranging from about 10 cm to about 60 cm and a width ranging from about 5 mm to about 16 mm. Moreover, the split in the split-tube650 can compose agap667 having a width ranging from about 4 mm to about 14 mm, the split accommodating a non-linearity in the surgical device. In some embodiments, the cutting heads taught herein can have a diameter that is smaller than that of the portion of the suction assembly that passes through the lumen of the guard cannula, such that the guard cannula holds thesuction assembly484 but allows the cuttinghead400 to pass through thegap667. As such, thegap667 can have a width that exceeds the diameter of the cuttinghead400 but is less than the diameter of therigid suction tube488, and the lumen of theguard cannula600 has a diameter that exceeds the diameter of therigid suction tube488.

A surgical tissue removal kit having a surgical tissue removal system and a guard cannula is provided, the kit using any combination of system and cannula embodiments taught herein. In some embodiments, the kits can be a discectomy kit. As such, in some embodiments, the entry tissue includes the subject's epithelial tissue, muscle tissue, nerve tissue, connective tissue, a blood vessel, bone, cartilage, or a combination thereof, leading to the nucleus pulposus. As such, the target tissue can include the nucleus pulposus in some embodiments.

FIG. 7 illustrates a surgical tissue removal kit, according to some embodiments. Thekit700 includes a cuttinghead400, asuction assembly484, and an obturator,guard cannula600. A flow ofsuction444 from thesuction assembly484 enters the cuttinghead400 to remove a target tissue excised by the cutting head.Irrigation water690 can enterirrigation valve795 and/or theirrigation port635, theirrigation water690 coming from theirrigation valve795 is used when thesuction444 is off, and theirrigation water690 coming from theirrigation port635 can be used when thesuction444 is on, during which thesuction444 draws theirrigation water690 between the luminal surface of theguard cannula600 and thesuction assembly484 into the surgical area (not shown). Theguard cannula600 protects the entry tissue (not shown) while the cuttinghead400 andsuction assembly484 moves relative to the entry tissue during a surgical procedure, the cuttinghead400 moving, for example, in a forward, backward, and/or transverse motion to excise and remove the target tissue.

A method of using the kits to remove a target tissue is provided. In some embodiments, the method comprises creating an opening in a subject for access to a target tissue; inserting the cutting head of the kit through the entry hub and the elongated split-tube of the guard cannula of the kit; inserting the cutting head of the kit through the opening to access the target tissue in the subject while protecting the entry tissue with the blunt, distal end of the split-tube. Otherwise, methods of using the tissue removal systems are the same or similar to those taught herein. One of skill will appreciate having such kits for discectomies, for example, in which the target tissue can be a nucleus pulposus, and the perimeter tissue can be an annulus fibrosis. One of skill will also appreciate having a kit with a guard cannula that helps protect the subject's epithelial tissue, muscle tissue, nerve tissue, connective tissue, a blood vessel, bone, cartilage, or a combination thereof, leading to the nucleus pulposus in such procedures.

FIGS. 8A-8C illustrate a system or kit that can irrigate concurrent with application of suction, and without the obturator, guard cannula in place, according to some embodiments.FIG. 8A shows thecomplete discectomy system800 including the cuttinghead400, a means for applying suction through thesuction assembly884, acontrol handle886 and avacuum attachment892, anirrigation tube804, anirrigation control802, and anoptional vacuum control888.

In embodiments in which the cutting head angle is adjustable, thehandle886 can have a knob (not shown) that turns to tension a pull cable to flex or straighten the cutting head relative to the rigid suction tube, or a slide that tensions the cable to flex or straighten the cutting head relative to the rigid suction tube. The cables to flex and straighten can be on opposing sides of the shaft constrained to small side lumens attached to the outer surface of the shaft to flex and straighten out the cutting head.

FIG. 8B shows a cross-sectional view of theirrigation tube804 relative to therigid suction tube894. And,FIG. 8C shows a cross-sectional view of the control handle886 and internal piping.

One of skill will appreciate that the teachings and examples provided herein are directed to basic concepts that can extend beyond any particular embodiment, embodiments, figure, or figures. It should be appreciated that any examples are for purposes of illustration and are not to be construed as otherwise limiting to the teachings.

Example 1Testing of Cutter Head Designs

A variety of cutter heads were tested in 3 cadaver laboratories on 28 discs. The results were compared to determine the most efficient cutter head design. A desirable cutter head design was one that would cut well on all target tissues, including the nucleus pulposus, vertebral endplates, and inner annulus tissue. However, the cutter head should also cut the target tissues in a desired manner while providing little to no damage to the perimeter tissue, such tissue including the perimeter annulus fibrosis tissue that should be preserved as a desirable perimeter structure. In addition, the design should remove tissue quickly under suction, such that the configuration of the head facilitates the removal of the tissue under suction.

FIGS. 9A-9H show cutting head designs that were tested, according to some embodiments. The design inFIG. 9A cut well but it was not as safe to the annulus as other designs. The design inFIG. 9B was safe to the annulus but it did not cut tough tissue well and showed too much resistance. The design inFIG. 9C also did not penetrate tough tissue well. The design inFIG. 9D did cut and decorticate well, but it clogged on soft/elastic tissue. The design inFIG. 9E cut tough tissue well and did not clog, and it also decorticates really well. It was also safe to the annulus. The shape of the device however, did not reach the far side of the nucleus pulposus. The design inFIG. 9F shows a bend that was introduced to the device to enable the cutting head ofFIG. 9E to reach the far side of the nucleus pulposus. The design inFIGS. 9G and 9H, however, showed the most efficient cutting head performance identified in the testing, removing 23 cc of material in 5 minutes.

Example 2

This example further developed the designs of the cutting heads. The design inFIGS. 8G and 8H were further investigated in 7 cadaver labs and 28 discs.

FIGS. 10A-10E illustrate the advancements in the cutting head, according to some embodiments. The design inFIG. 10A shows a cutting head having a bevel on the outer surface of the cutting teeth, and the device cut poorly and gouged soft bone. The design inFIG. 10B shows an oval cutting head not having the bevel on the outer surface of the cutting teeth, and the device had inconsistent cutting and gouged soft bone. The design inFIG. 100 was shown for a comparison result using a ring curette, and the device gouged soft bone. The design inFIG. 10D shows a short cutting head with a single “talon” or pincer, and the device showed the most appealing results to date with optimal cutting and no gouging.FIG. 10E is another proposed design, configured to perform with the efficiency of the design ofFIG. 10D, with the addition of a second talon that bends away from the lumen of the cutting head to serve as an additional talon and blade guard.

The method used in this example was as follows:

1. Cutting a pilot hole of a 5-8 mm dimension in height and width;
2. Pointing a 15° tip parallel to the vertebral endplates to cut and expand the cavity medially and laterally;
3. Gradually shaving down the endplates to hard tissue (cartilage or bone); fluoroscopy was used to verify the depth of the tip; the tip was used to shave along the curvature of the endplate; shaving was stopped where bone was exposed (hard, rough, sticky, and red aspirate identified as the endpoint); and, the handle of the device is tilted (i) medially to decorticate lateral side, and (ii) laterally to decorticate medial side;
4. Sweeping the cutting head medially-laterally against anterior annulus to remove nucleus attached to the annulus and inner annulus as needed;
5. Pointing a 40° tip contralaterally and start shaving from posterior annulus while tilting handle laterally to remove bulk nucleus; and,
6. Rotating the handle toward the endplate to further decorticate.

Example 3

This example describes an alternate embodiment that was tested, referred to as the serpentine or bayonet configuration, in which therigid suction tube488 can have at least two angles; an angle θ₁, and an angle θ₃.

FIGS. 11A-11C illustrate a bayonet-type communication between a cutting head and a suction assembly, according to some embodiments. It was discovered that the distal end of therigid suction tube488 can be redirected in bayonet, or serpentine, fashion in order to facilitate an improved access of the cutting head to a target tissue during a discectomy, for example. As shown inFIGS. 11A-11C, Angles θ₁and θ₃can each be independently selected to range from about 0° to about 180°, with the limitation that (i) the net angle, θ₄, that is realized between thecentral axis415 of thelumen410 of the cuttinghead400 and thecentral axis497 of the rigid suction tube488 (extended as directed proximal to θ₁) ranges from 0° to 90°; and, (ii) thedistance498 between thecentral axis415 of thelumen410 of the cuttinghead400 and thecentral axis497 of therigid suction tube488 can range from about 2 mm to about 30 mm. And, in these embodiments, the central axis of the lumen can have a point of exit at the forward cutting blade, and the point of exit is located at a transverse distance of about 3 mm to about 25 mm

In some embodiments, thedistance498 between the from about 2.5 mm to about 25 mm, from about 3 mm to about 25 mm, from about 4 mm to about 20 mm, from about 5 mm to about 15 mm, from about 3 mm to about 25 mm, from about 7 mm to about 12 mm, from about 8 mm to about 10 mm, or any range therein in increments of 0.5 mm. As such, thedistance498 can be about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 12 mm, about 14 mm, about 16 mm, about 18 mm, about 20 mm, about 22 mm, about 24 mm, about 26 mm, about 28 mm, about 30 mm, and any distance or range therein in increments of 0.5 mm. In some embodiments, the distance between the vertex of θ₃and the distal end of the cuttinghead400 can range from about 5 mm to about 25 mm, from about 6 mm to about 20 mm, from about 7 mm to about 15 mm, or any range therein in increments of 1 mm.